Valve connectors of this type are known, e.g. from the documents U.S. Pat. Nos. 5,242,342, 5,676,346, 6,706,022, 5,700,248 and 6,682,509.
More in particular, the documents U.S. Pat. Nos. 5,700,248 and 6,682,509 describe a valve connector according to the preamble to claim 1, which provides a tubular body having a cavity, an inlet end adapted for the engagement of an introducer of liquid, and an outlet end. A hollow pin is arranged axially within the cavity of the tubular body and has a closed terminal oriented towards the inlet end of the tubular body and axially distanced therefrom. The hollow pin is in communication with the outlet end of the tubular body and has at least a lateral hole distanced from its terminal for communication with the cavity of the tubular body. The connector further includes an elastic sealing member which comprises an elastic head having a pre-slotting and normally arranged in a closed condition (or inactive condition) within the inlet end of the tubular body in which the pre-slotting is closed, and axially movable against the terminal of the hollow pin by effect of the insertion of said introducer into the inlet end, to interact with said terminal assuming an elastically deformed open configuration (or active condition) in which the pre-slotting is opened. The elastic sealing member of the valve connector further comprises an elastic hollow element joined to the head and interposed between the tubular body and the hollow pin to isolate the cavity of the tubular body relative to its outlet end. Said elastic hollow element defines an elastic thrust means which tends to maintain the head in its closed condition, and has an internal contact surface with the hollow pin to isolate the aforesaid at least one lateral hole relative to the cavity of the tubular body when the head is in the closed condition.
Valve connectors of this type must meet a series of fundamental requirements, since their use is often critical for the survival of the patients who utilize them.
In the first place, the closure of the inlet end of the tubular body operated by the head of the elastic member must be substantially tight, thereby assuring a total anti-bacterial barrier, even after repeated opening and re-closings of the valve connector.
Secondly, the opening and re-closing operation of the communication between the inlet end and the outlet end of the connector upon the insertion and respectively of the extraction of the introducer must be wholly reliable and repeatable without even minimal risk of malfunctions which could entail severe risks for the patient connected to the valve connector. For this reason, the number of moving mechanical member of the valve connector must be as small as possible.
Thirdly, these connectors must be able effectively to support any over-pressures which may be generated within them in sue and in the closed or inactive condition, and assure an effective seal against positive and negative.
Lastly, these valve connectors must be easily cleaned and disinfected from the side of the inlet end, typically with a wad imbued with disinfectant.
In the case of the valve connectors known from the aforementioned documents U.S. Pat. Nos. 5,700,248 and 6,682,509, the opening of the communication between the inlet end of the tubular body and the outlet end, through the lateral hole or holes of the hollow pin upon the engagement of the introducer, is achieved as a result of the crossing of the pre-slotting of the elastic head by the terminal of the hollow pin. The hollow element of the elastic member has a corrugated or bellow-shaped wall, so that its axial compression produces a collapse thereof in the manner of an accordion. The axial compression of the hollow element is such that the elastic head flows along the hollow pin until it is positioned below the lateral hole or holes thereof, thereby directly exposing these lateral holes to the flow coming from the introducer.
This arrangement essentially has the drawback that the sealing of the lateral hole or holes of the hollow pin, in the condition of closure of the valve connector, is entrusted solely to the radial elasticity of the hollow element of the elastic member. Moreover, the crossing of the pre-slotting of the elastic head by the terminal of the hollow pin upon opening the valve connector, together with the engagement of the related closed terminal into the introducer, may entail risks of malfunctions in addition to limitations in relation to the minimum diameter of the introducers which can be used with said known valve connectors.